The present invention relates to a series of new pyridazinone derivatives which have fungicidal activity, and provides a method of preparing these compounds and agricultural fungicidal compositions containing them.
A number of pyridazinone derivatives is known to have fungicidal activity. For example, those disclosed in United Kingdom Patent Specification No. 1,533,010, which may be represented by the formula: ##STR4## (in which R.sup.a may represent a hydrogen atom, a hydroxy group or an acyloxy group, R.sup.b and R.sup.d both represent halogen atoms or one represents a halogen atom and the other represents a hydrogen atom, R.sup.c represents, inter alia, a hydrogen or halogen atom or an alkyl or alkoxy group, and R.sup.e represents a hydrogen atom) have been found to be effective against a wide range of pathogenic fungi whilst not exhibiting any phytotoxicity, when employed at effective doses. Spanish Pat. No. 467,728 discloses processes for preparing some of the same compounds as are disclosed in United Kingdom Patent Specification No. 1,533,010 and also discloses a number of previously unknown, but related compounds, including some in which R.sup.e in the above formula represents an alkyl group.
Subsequently, United Kingdom Patent Specification No. 2,047,702A disclosed a series of compounds similar to those of the above formula but in which either the carbonyl group on the pyridazine ring has been replaced by a N-substituted carbamoyloxy group (or the sulphur analogue in which one or both of the oxygen atoms in the carbamoyloxy group has been replaced by a sulphur atom) or in which there is an alkyl-, aryl- or aralkyl-oxy (or thio) carbonyl group on the nitrogen atom adjacent the pyridazinone carbonyl group.
We have now discovered a series of compounds which are related to the prior art compounds described above but which are chemically more stable than those of United Kingdom Patent Specification No. 2,047,702A and which have greater systemic (i.e. penetrating) activity than do those of United Kingdom Patent Specification No. 1,533,010 and Spanish Pat. No. 467,728.